Thin film encapsulation unit having a reflection-preventing layer on an organic layer

ABSTRACT

A thin film encapsulation unit including an inorganic layer, a first organic layer on the inorganic layer and including a light-blocking unit and a light-transmitting unit, and a reflection-preventing layer on the first organic layer.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean PatentApplication No. 10-2012-0102383 filed in the Korean IntellectualProperty Office on Sep. 14, 2012, the entire contents of which areincorporated herein by reference.

BACKGROUND

1. Field

The described technology relates generally to an organic light emittingdiode (OLED) display.

2. Description of the Related Art

An organic light emitting diode display includes organic light emittingelements that include a hole injection electrode, an organic emissionlayer, and an electron injection electrode. Each organic light emittingelement emits light by energy generated when excitons that are generatedby combining electrons and holes in the organic emission layer fall froman exited state to a bottom state/ground state, and the organic lightemitting diode display displays images by using this light emission.

Because the organic light emitting diode display has the characteristicof self-luminance, and therefore, unlike a liquid crystal display, aseparate light source is not required, and thickness and weight of theorganic light emitting diode display may be reduced. Further, becausethe organic light emitting diode display exhibits high qualitycharacteristics such as low power consumption, high luminance, and rapidresponse speed, the organic light emitting diode display receivesattention as a next generation display device.

Such an OLED display extracts generated light by resonance, whilereflection in a thin film transistor, a capacitor, a driver, and asignal line in a non-light-emission area causes deterioration ofcontrast.

Thus, a circular polarizer film is used to improve contrast. Thecircular polarizer film includes a linear polarizer film and a phasedifference film according to a method for bonding multiple films. Such acircular polarizer film is attached after deposition of a thin filmencapsulation of a display panel. However, because the circularpolarizer film may be as thick as 200 μm, the display device cannot beas slim, and production cost is increased.

The above information disclosed in this Background section is only forenhancement of understanding of the background of the describedtechnology, and may therefore contain information that does not form theprior art that is already known in this country to a person of ordinaryskill in the art.

SUMMARY

Embodiments of the present invention provide an OLED display that canimprove contrast without using a circular polarizer film, can be formedslim, and can reduce production cost, and a method for manufacturing theOLED display.

A thin film encapsulation unit according to an exemplary embodimentincludes an inorganic layer, a first organic layer on the inorganiclayer and including a light-blocking unit and a light-transmitting unit,and a reflection-preventing layer on the first organic layer.

The thin film encapsulation unit may further include a second organiclayer including a transparent material on the inorganic layer.

The thin film encapsulation unit may further include a plurality ofsecond organic layers and a plurality of inorganic layers, wherein thesecond organic layers and the inorganic layers are iteratively layered.

The thin film encapsulation unit may further include a plurality offirst organic layers and a plurality of inorganic layers, wherein theinorganic layers and the first organic layers are alternately layered.

The light-blocking unit may include an organic material including ablack pigment.

The reflection-preventing layer may include a metal layer and adielectric material layer.

Transmittance of the reflection-preventing layer may be about 30% toabout 70%.

The metal layer may include at least one of chromium (Cr), molybdenum(Mo), titanium (Ti), tungsten (W), or an alloy thereof.

The dielectric material layer may include a high-refractive index layerand a low-refractive index layer, wherein the high-refractive indexlayer includes a material having a refractive index of about 1.6 orhigher, and wherein the low-refractive index layer includes a materialhaving a refractive index of less than about 1.6.

The reflection-preventing layer may include a first chromium layer, afirst silicon oxide layer, a second chromium layer, a titanium oxidelayer, and a second silicon oxide layer.

An OLED display according to the present invention includes a substrateon which an organic light emitting element is located, an inorganiclayer and an organic layer on the substrate and covering the organiclight emitting element, and a reflection-preventing layer on the organiclayer, wherein the organic layer includes a light-blocking unit and alight-transmitting unit.

The substrate may include a light-emission area where the organic lightemitting element is located, and a non-light-emission area including anarea other than the light-emission area, wherein the light-blocking unitof the organic layer corresponds to the non-light-emission area, andwherein the light-transmitting unit corresponds to the light-emissionarea.

The organic light emitting element may include a first electrode, anorganic emission layer, and a second electrode, and the light-emissionarea may correspond to the organic emission layer.

The OLED display may further include a plurality of inorganic layers anda plurality of organic layers, wherein the inorganic layers and theorganic layers are alternately layered.

The organic layer may further include a transparent organic layerincluding a transparent organic material.

The reflection-preventing layer may include a metal layer and adielectric material layer.

Transmittance of the reflection-preventing layer may be about 30% toabout 70%.

The metal layer may include at least one of chromium (Cr), molybdenum(Mo), titanium (Ti), tungsten (W), or an alloy thereof.

The dielectric material layer may include a high refractive index layerand a low refractive index layer, wherein the high refractive indexlayer includes a material having a refractive index of about 1.6 orhigher, and wherein the low refractive index layer includes a materialhaving a refractive index of less than about 1.6.

The reflection-preventing layer may include a first chromium layer, afirst silicon oxide layer, a second chromium layer, a titanium oxidelayer, and a second silicon oxide layer.

The OLED display may further include a transistor on the substrate, aninterlayer insulating layer on the transistor, a first electrode of theorganic light emitting element on the interlayer insulating layer andcoupled with the transistor through a contact hole, a pixel defininglayer on the interlayer insulating layer and having an opening thatexposes the first electrode, an organic emission layer of the organiclight emitting element in the opening, and a second electrode of theorganic light emitting element on the organic emission layer and thepixel defining layer, wherein the light-blocking unit has a planepattern that is the same as that of the pixel defining layer.

A method for manufacturing an OLED display according to anotherexemplary embodiment includes forming a substrate on which an organiclight emitting element is formed, forming an inorganic layer on thesubstrate, forming an organic layer including a light-transmitting unitand a light-blocking unit on the inorganic layer using an inkjetprinting method, and forming a reflection-preventing layer on theorganic layer.

The light-blocking unit may include an organic material that includes ablack pigment, and the light-transmitting unit may include a transparentorganic material.

The method may further include forming a transparent organic layerincluding a transparent organic material on the inorganic layer afterforming the inorganic layer.

When the thin film encapsulation unit formed according to an exemplaryembodiment of the present invention is used, contrast can be improvedwithout using a thick polarization plate.

In addition, since the thick polarization plate is not used, the OLEDdisplay can be formed slim by reducing the thickness of the OLED displayand a flexible characteristic can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a thin film encapsulation unitaccording to an exemplary embodiment of the present invention.

FIG. 2 to FIG. 4 are cross-sectional views of a thin film encapsulationunit according to other exemplary embodiments of the present invention.

FIG. 5 is an equivalent circuit of a pixel of an organic light emittingdiode (OLED) display according to an exemplary embodiment of the presentinvention.

FIG. 6 is a cross-sectional view of the pixel of the OLED display of theembodiment shown in FIG. 5.

FIG. 7 is a top plan view of a pixel defining layer according to anexemplary embodiment of the present invention.

FIG. 8 is a graph measuring light efficiency characteristics of aconventional OLED display and of an OLED display according to anexemplary embodiment of the present invention.

FIG. 9 to FIG. 11 are cross-sectional views depicting a method formanufacturing the OLED display according to an exemplary embodiment ofthe present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described more fullyhereinafter with reference to the accompanying drawings, in whichexemplary embodiments of the present invention are shown. As thoseskilled in the art would realize, the described embodiments may bemodified in various different ways, all without departing from thespirit or scope of the present invention.

The drawings and description are to be regarded as illustrative innature and not restrictive. Like reference numerals designate likeelements throughout the specification.

In the drawings, the size and thickness of each element may bearbitrarily shown, and the present invention is not necessarily limitedthereto. Further, the thickness of layers, films, panels, regions, etc.,may be exaggerated for clarity, and the thickness of some of layers andregions may be exaggerated for the sake of explanation. It will beunderstood that when an element such as a layer, film, region, or plateis referred to as being “on” another element, it can be directly on theother element, or one or more intervening elements may also be present.

In addition, unless explicitly described to the contrary, the word“comprise” and variations thereof, such as “comprises” or “comprising,”will be understood to imply the inclusion of stated elements, but notnecessarily the exclusion of any other elements. Also, throughout thespecification, “on” means that an element is positioned on or aboveanother element, or under or below another element, and may notnecessarily mean that an element is positioned at an upper side of theother element with respect to a direction of gravity.

Hereinafter, an organic light emitting diode (OLED) display according toan exemplary embodiment will be described with reference to theaccompanying drawings.

FIG. 1 is a cross-sectional view of a thin film encapsulation unitaccording to an exemplary embodiment of the present invention. As shownin FIG. 1, a thin film encapsulation unit 1001 according to theexemplary embodiment includes at least one of an inorganic layer 201, afirst organic layer 203, and a second organic layer 205. The thin filmencapsulation unit 1001 may have a thickness of, for example, less than10 μm.

In multi-layering, the inorganic layer 201, or multiple layers thereof,and the first organic layer 203, or multiple layers thereof, or theinorganic layer 201, or multiple layers thereof, and the second organiclayer 205, or multiple layers thereof, may be alternately layered. Also,the inorganic layer 201, the first organic layer 203, and the secondorganic layer 205 may be alternately layered.

The inorganic layer 201 may be located between neighboring organiclayers 203 and 205 among a plurality of organic layers 203 and 205, andmay be the lowest/bottommost or the highest/topmost layer of the thinfilm encapsulation unit 1001. The inorganic layer 201 has excellentwaterproofing characteristics when compared to the organic layers 203and 205.

The inorganic layer 201 may be a single layer or may be multilayerincluding at least one of aluminum oxide, such as silicon oxide (SiOx),silicon nitride (SiNx), titanium oxide (TiOx), alumina (Al₂O₃), and thelike, and silicon oxynitride.

The first organic layer 203 and the second organic layer 205 have weakerwaterproofing properties when compared to the inorganic layer 201, buthave flexibility so that the first and second organic layers 203 and 205can improve deficiencies of the organic layer 201, which is harder thanthe first and second organic layers 203 and 205.

The first organic layer 203 includes a light-blocking unit 25 forblocking light and a light-transmitting unit 27 for transmitting light.The light-transmitting unit 27 may be formed of a transparentlight-transmissive material, for example a resin such as polyethyleneterephthalate (PET), polyacrylate, polyimide (PI), and polycarbonate(PC), and the like. The light-blocking unit 25 may be formed of amaterial having low transmittance to absorb light, and may be formed ofan organic material including a black pigment. The organic material mayinclude, for example, an acryl resin, a silicon resin, and an epoxyresin.

The second organic layer 205 is a light-transmissive material, and maybe formed of the same material of the light-transmitting unit 27 of thefirst organic layer 203.

The thin film encapsulation unit according to the exemplary embodimentimproves contrast of the display device.

The display device including the organic light emitting element includesa display area and a non-display area. The display area is an area wherean organic emission layer of the organic light emitting element islocated, while the non-display area is the remaining areas of thedisplay area.

In the present embodiment, in the display device, the light-blockingunit of the thin film encapsulation unit is located in the non-displayarea, and the light-transmitting unit is located in the light-emissionarea. Thus, the light-blocking unit reduces or eliminates lightreflected by the non-light-emission area by absorbing the light, therebyimproving contrast.

The thin film encapsulation unit may have various structures, as shownin FIG. 2 to FIG. 4. FIG. 2 to FIG. 4 are cross-sectional views of thinfilm encapsulation units according to other exemplary embodiments of thepresent invention.

As shown in FIG. 2, a thin film encapsulation unit 1002 includes atleast one of an inorganic layer 201, a first organic layer 203, and asecond organic layer 205. The thin film encapsulation unit 1002 issimilar to the thin film encapsulation unit 1001 of FIG. 1, andtherefore, only differences thereof will be described in further detail.

In FIG. 2, the thin film encapsulation unit 1002 further includes areflection-preventing layer 300 formed on the uppermost inorganic layer201. The reflection-preventing layer 300 includes at least one of ametal layer and a dielectric material layer, and may have a thicknessof, for example, less than 1 μm. The metal layer and the dielectricmaterial layer may be alternately layered.

The metal layer may be formed of at least one of chromium (Cr),molybdenum (Mo), titanium (Ti), tungsten (W), and an alloy thereof, andmay be formed as a single layer or as a multilayer (e.g., multiplelayers).

The dielectric material layer includes at least one of a high-refractiveindex layer and a low-refractive index layer, and the high-refractiveindex layer may have a refractive index of, for example, about 1.6 orhigher, and may be chromium (Cr) or titanium oxide (TiO₂), and thelow-refractive index layer may have a refractive index of, for example,lower than about 1.6, and may be SiO₂.

The reflection-preventing layer 300 reduces or blocks inflow ofundesired external light to the display device, and allows light emittedfrom the organic light emitting element to be emitted to the outside,rather than being reflected. Therefore, transmittance of thereflection-preventing layer 300 may be, for example, about 30% to about70%, and preferably about 43%.

A thin film encapsulation unit 1003 of FIG. 3 includes at least one ofan inorganic layer 201, a first organic layer 203, and a second organiclayer 205. The thin film encapsulation unit 1003 is similar to the thinfilm encapsulation unit 1002 of FIG. 2, and therefore only differencesthereof will be described in further detail.

In the thin film encapsulation unit 1003 of FIG. 3, areflection-preventing layer 300 is formed on the second organic layer205. Thus, deterioration of contrast occurring due to reflection by theinorganic layer 201 between the reflection-preventing layer 300 and thesecond organic layer 205 can be prevented or reduced.

In addition, a thin film encapsulation unit 1004 of FIG. 4 includes atleast one of an inorganic layer 201 and a first organic layer 203. Thethin film encapsulation unit 1004 is almost the same as the thin filmencapsulation unit 1001 of FIG. 1, and therefore only differencesthereof will be described in further detail.

A thin film encapsulation unit 1004 of FIG. 4 can reduce or preventdeterioration of contrast due to reflection by the second organic layer205 (see FIGS. 2 and 3) by iteratively, or alternatingly, layering theinorganic layer 201 and the first organic layer 203.

An OLED display including the thin film encapsulation unit, according toembodiments of the present invention, will be described in furtherdetail with reference to FIG. 5 to FIG. 7.

FIG. 5 is an equivalent circuit diagram of a pixel of the OLED displayaccording to an exemplary embodiment of the present invention. As shownin FIG. 5, a pixel P of the OLED display has a 2Tr-1Cap structure inwhich an organic light emitting diode 70, two thin film transistors(TFTs) Q1 and Q2, and one capacitor 80 are arranged. However, theexemplary embodiment is not limited thereto. Thus, in another exemplaryembodiment, one pixel of the OLED display 1001 may have a structure inwhich three or more thin film transistors and/or two or more capacitorsare arranged, and various other structures with additional wirings. Theadditional thin film transistor and capacitor may form a compensationcircuit, which suppresses deviation in image quality by improvinguniformity of operation of an organic light emitting diode 70 formed ineach pixel P. In general, the compensation circuit includes 2 to 8 thinfilm transistors.

The organic light emitting element 70 includes an anode, which is a holeinjection electrode, a cathode, which is an electron injectionelectrode, and an organic emission layer located between the anode andthe cathode.

Each pixel P according to the present exemplary embodiment includes afirst thin film transistor Q1 and a second thin film transistor Q2. Thefirst thin film transistor Q1 and the second thin film transistor Q2respectively include gate electrodes, semiconductors, source electrodes,and drain electrodes. In addition, a semiconductor of at least one ofthe first thin film transistor Q1 and the second thin film transistor Q2includes a polysilicon layer doped with an impurity, an amorphoussilicon layer, and microcrystalline silicon.

FIG. 5 illustrates a gate line 121, a data line 171, a constant voltageline 172, and a capacitor line 131, although the capacitor line 131 maybe omitted as necessary or desired. The gate line 121 and the data line171 of FIG. 5 may respectively be a first signal line and a secondsignal line.

The data line 171 is coupled with a source electrode of the first thinfilm transistor Q1, and a gate electrode of the first thin filmtransistor Q1 is coupled with the gate line 121. In addition, a drainelectrode of the first thin film transistor Q1 is coupled to thecapacitor line 131 through the capacitor 80. A node is formed betweenthe drain electrode of the first thin film transistor Q1 and thecapacitor 80, and thus a gate electrode of the second thin filmtransistor Q2 is coupled to the node. In addition, a source electrode ofthe second thin film transistor Q2 is coupled with the constant voltageline 172, and a drain electrode thereof is coupled with the anode of theorganic light emitting element 70.

The first thin film transistor Q1 is used as a switch to select a pixelP for light emission. When the first thin film transistor Q1 is turnedon, the capacitor 80 is charged, and the amount of charge isproportional to a voltage applied from the data line 171. In addition,when a voltage increasing signal is input for each frame cycle to thecapacitor line 131 while the first thin film transistor Q1 is turnedoff, a gate potential of the second thin film transistor Q2 is increasedin accordance with (or pursuant to) the voltage applied through thecapacitor line 131. Here, the voltage has a level of a voltage appliedwith reference to the potential charged in the capacitor 80. The secondthin film transistor Q2 is turned on when the gate potential thereofexceeds a threshold voltage of the second thin film transistor Q2. Then,a voltage applied to the constant voltage line 172 is applied to theorganic light emitting element 70 through the second thin filmtransistor Q2 such that the organic light emitting element 70 emitslight.

FIG. 6 is a cross-sectional view of the pixel of the OLED display of theembodiment shown in FIG. 5, and FIG. 7 is a top plan view of a pixeldefining layer according to an exemplary embodiment of the presentinvention.

Referring to FIG. 6, a structure of the OLED display, particularly thesecond thin film transistor Q2 and the organic light emitting element 70of FIG. 5, will be described in detail according to the laminationorder. Hereinafter, the second thin film transistor Q2 will be referredto as a thin film transistor.

As shown in FIG. 6, a buffering layer 120 that prevents or reducespermeation of unnecessary or undesired components, such as impurities ormoisture, and that also planarizes the surface, is formed on thesubstrate 100.

A semiconductor 135 formed of polysilicon is formed on the bufferinglayer 120, and is divided into a channel area 1355, a source area 1356,and a drain area 1357. The source area 1356 and the drain area 1357 areformed at respective sides of the channel area 1355, the channel area1355 including polysilicon not doped with an impurity, that is, thechannel area 1355 is an intrinsic semiconductor. The source area 1356and the drain area 1357 of the semiconductor 135 are polysilicon dopedwith a conductive impurity (i.e., impurity semiconductors). The impuritydoped to the source area 1356 and the drain area 1357 may be one of ap-type impurity or an n-type impurity.

A gate insulating layer 140 is formed on the semiconductor 135, and maybe a single layer or multilayer including at least one of tetraethylorthosilicate (TEOS), silicon nitride, or silicon oxide.

A gate electrode 155 is formed on the gate insulating layer 140, andoverlaps the channel area 1355.

An interlayer insulating layer 60 is formed on the gate electrode 155.Like the gate insulating layer 140, the interlayer insulating layer 160may be formed of tetraethyl orthosilicate (TEOS), silicon nitride, orsilicon oxide.

The interlayer insulating layer 160 and the gate insulating layer 140have a source contact hole 166 and a drain contact hole 167 respectivelyexposing the source area 1356 and the drain area 1357.

A source electrode 177 and a drain electrode 176 are formed on theinterlayer insulating layer 160. The source electrode 177 is coupledwith the source area 1356 through the source contact hole 166, and thedrain electrode 176 is coupled with the drain area 1357 through thedrain contact hole 167.

A protective layer 180 is formed on the interlayer insulating layer 160.The protective layer 180 has a contact hole 185 that exposes the drainelectrode 176.

A first electrode 710 coupled with the drain electrode 176 through thecontact hole 185 is formed on the protective layer 180. The firstelectrode 710 becomes the anode of the organic light emitting element ofFIG. 5.

A pixel defining layer 190 is formed on the first electrode 710, and hasan opening 195 exposing the first electrode 710. The pixel defininglayer 190 may include a resin such as, for example, polyacrylates orpolyimides, and an inorganic material such as silica.

An organic emission layer 720 is formed in the opening 195 of the pixeldefining layer 190, and is formed as a multilayer including one or moreof a light emission layer, a hole injection layer (HIL), a holetransport layer (HTL), an electron transport layer (ETL), and anelectron injection layer (EIL). When the organic emission layer 720includes all of the above, then the electron injection layer is locatedon the negative electrode 710, on which the electron transport layer,the organic emission layer, the hole transport layer, and the holeinjection layer are then sequentially stacked.

A second electrode 730 is formed on the pixel defining layer 190 and theorganic emission layer 720, and becomes the cathode of the organic lightemitting element 70 of FIG. 5. Thus, the first electrode 710, theorganic emission layer 720, and the second electrode 730 form theorganic light emitting element 70.

The OLED display may be structured as any one of a front-display type, arear-display type, and a single-panel dual-display type, depending uponthe light-emitting direction of the organic light emitting diode 70.

If the OLED display is structured as the front-display type, the firstelectrode 710 is formed with a reflective film, and the second electrode730 is formed with a semitransparent film. If the OLED display isstructured as the rear-display type, the first electrode 710 is formedwith a semitransparent film, and the second electrode 730 is formed witha reflective film. If the OLED display is structured as the single-paneldual-display type, the first electrode 710 and the second electrode 730are formed with a transparent film or a semitransparent film.

The reflective film and the semitransparent film are formed with atleast one metallic material selected from magnesium (Mg), silver (Ag),gold (Au), calcium (Ca), lithium (Li), chromium (Cr), aluminum (Al), andalloys thereof. Whether a given film is a reflective film or asemitransparent film is determined depending upon the thickness thereof.With the semitransparent film, the smaller the thickness is, the morelight transmittance is increased, and the more resistance is reduced.

The transparent film may be formed with, for example, indium tin oxide(ITO), indium zinc oxide (IZO), zinc oxide (ZnO), or indium oxide(In2O3).

A thin film encapsulation unit 500 is formed on the second electrode730. In the exemplary embodiment of the present invention shown in FIG.6, the inorganic layer 201 and the second organic layer 205 areiteratively layered twice, and then the inorganic layer 201, the firstorganic layer 203, and the reflection-preventing layer 300 aresequentially layered. In present exemplary embodiment, the inorganiclayer 201 and the second organic layer 205 are iteratively layered.Thereafter, just the first organic layer 203 may be layered thereon, oralternatively, multiple first and second organic layers 203 and 205 maybe alternately layered thereon. Furthermore, the layering may berepeated once, twice, three times, or more than three times.

In addition, the thin film encapsulation units 1001-1004 of FIG. 1 toFIG. 4 may be included.

A light-transmitting unit 27 of the thin film encapsulation unit 500 maybe located in an area that corresponds to the organic emission layer720, and a light-blocking unit 25 may be formed in areas that do notinclude the organic emission layer 720. As shown in FIG. 7, thelight-blocking unit 27 may have the same plane pattern as the pixeldefining layer 190.

As in the present exemplary embodiment, reflection of external lightincident on the display device can be effectively reduced or eliminatedby forming the thin film encapsulation unit 500 such that contrast ofthe OLED display can be improved.

That is, external light incident on the display device is reflected tovarious thin films included in the display device, but reduced oreliminated by being absorbed by the light-blocking unit 25 of the thinfilm encapsulation unit, and therefore image quality formed by lightemitted from the organic light emitting element of the display can beimproved by reducing or preventing deterioration due to reflection ofthe external light. Accordingly, the contrast of the display device canbe improved.

In addition, the reflection-preventing layer 300 of the thin filmencapsulation unit 500 can reduce or prevent inflow of unwanted orunnecessary external light to the display device, and can allow lightemitted from the organic light emitting element to be emitted to theoutside, rather than being reflected. Accordingly, reflection of theexternal light can be reduced, and contrast can be improved.

FIG. 8 is a graph of measured light efficiency characteristics of aconventional OLED display, and of an OLED display according to anexemplary embodiment of the present invention. In the graph of FIG. 8, aconventional display device uses an encapsulation substrate formed ofglass, and the display device according to the present exemplaryembodiment is the OLED display of the embodiment shown in FIG. 6.

As shown in the graph of FIG. 8, transmittance of the display deviceaccording to the exemplary embodiment and transmittance of theconventional display device are similar to each other.

Table 1 shows a contrast ratio (CR) of the conventional display deviceand the OLED display according to the present exemplary embodiment. InTable 1, the conventional display device uses an encapsulation substrateformed of glass, and a circular polarization plate is attached onto theencapsulation substrate, while the display device according to thepresent exemplary embodiment is the OLED display of the embodiment shownin FIG. 6.

TABLE 1 Ambient light illumination (Lux) 0 150 500 1,000 5,000 100,000200,000 CR of Polarizer 33700 199.3 43.3 19.0 4.2 2.5 1.84 CR of 43% AR& 32691 182 44 20.4 4.3 2.6 1.84 BM *CR: contrast ratio

As shown in Table 1, a contrast of the display device according to theexemplary embodiment is similar to a contrast of the conventionaldisplay device.

As described, when the thin film encapsulation unit is used as in theexemplary embodiment, the display device can acquire the sametransmittance characteristic and the same contrast ratio without using apolarization plate having a thickness of several hundreds μm and a heavyglass encapsulation substrate. Accordingly, the thickness of the displaydevice can be reduced, and a flexible characteristic can be improved.

Hereinafter, a method for manufacturing an OLED display according to anexemplary embodiment of the present embodiment will be described withreference to FIG. 9 to FIG. 11. FIG. 9 to FIG. 11 are cross-sectionalviews that sequentially illustrate a manufacturing method of the OLEDdisplay according to an exemplary embodiment of the present invention.

As shown in FIG. 9, the thin film transistor Q2 and the organic lightemitting element 70 are formed on the substrate 100. In addition, theinorganic layer 201 and the second organic layer 205 are formed byalternately layering the inorganic layer 201 and the second organiclayer 205 on the organic light emitting element 70. The inorganic layer201 and the second organic layer 205 may be formed by, for example,sputtering, E-beam, CVD, and the like.

Next, as shown in FIG. 10, the light-transmitting unit 27 of the firstorganic layer 203 is formed on the inorganic layer 201. Thelight-transmitting unit 27 may be formed of a transparent organicmaterial, and is formed using an inkjet printing method in only alight-emission area that corresponds to the organic emission layer 720.

Then, as shown in FIG. 11, the first organic layer 203 is completed byforming the light-blocking unit 25 on the inorganic layer 201 thatcorresponds to a non-light-emission area. The light-blocking unit 25 isan organic material including a black pigment, and may be formed usingan inkjet printing method, like the light-transmitting unit 27.

Next, as shown in FIG. 6, the reflection-preventing layer 300 is formedon the first organic layer 203, and may be formed by layering the metallayer and the dielectric material layer, and may be formed usingsputtering, E-beam, CVD, or flash evaporation, and the like.

While this disclosure has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims and their equivalents.

What is claimed is:
 1. A thin film encapsulation unit comprising: aninorganic layer; a first organic layer on the inorganic layer andcomprising a light-blocking unit and a light-transmitting unit; a secondorganic layer comprising a transparent material; and areflection-preventing layer on the first organic layer, wherein anentirety of the light-transmitting unit in the thin film encapsulationunit is made of a same transparent organic material, wherein theinorganic layer is located between the first organic layer and thesecond organic layer, and wherein the light-transmitting unit and thesecond organic layer are made of the same transparent organic material.2. The thin film encapsulation unit of claim 1, further comprising asecond organic layer comprising a transparent material on the inorganiclayer.
 3. The thin film encapsulation unit of claim 2, furthercomprising a plurality of second organic layers and a plurality ofinorganic layers, wherein the second organic layers and the inorganiclayers are iteratively layered.
 4. The thin film encapsulation unit ofclaim 1, further comprising a plurality of first organic layers and aplurality of inorganic layers, wherein the inorganic layers and thefirst organic layers are alternately layered.
 5. The thin filmencapsulation unit of claim 1, wherein the light-blocking unit comprisesan organic material comprising a black pigment.
 6. The thin filmencapsulation unit of claim 1, wherein the reflection-preventing layercomprises a metal layer and a dielectric material layer.
 7. The thinfilm encapsulation unit of claim 6, wherein transmittance of thereflection-preventing layer is about 30% to about 70%.
 8. The thin filmencapsulation unit of claim 6, wherein the metal layer comprises atleast one of chromium (Cr), molybdenum (Mo), titanium (Ti), tungsten(W), or an alloy thereof.
 9. The thin film encapsulation unit of claim6, wherein the dielectric material layer comprises a high-refractiveindex layer and a low-refractive index layer, wherein thehigh-refractive index layer comprises a material having a refractiveindex of about 1.6 or higher, and wherein the low-refractive index layercomprises a material having a refractive index of less than about 1.6.10. The thin film encapsulation unit of claim 6, wherein thereflection-preventing layer comprises a first chromium layer, a firstsilicon oxide layer, a second chromium layer, a titanium oxide layer,and a second silicon oxide layer.